The strangest thing happened today. Normally, when I tap the shell of my girls' eggs, it sounds, well, like an egg. But today, I tapped the shell of an egg laid today, and it had this very distinctly metallic sound to it. It really sounds like the shell is made of metal - it's so weird! I only have two hens and no rooster. I did feed her a large chunk of sardine - maybe that has something to do with it? Any thoughts on this? Thanks!!!